When lava flows, hot springs, geysers, etc., are naturally cooled by the climate they interact with when they reach the surface, how is core temperature sustainable?
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It does and it doesn’t. Over time, the center of the Earth is going to cool down, resulting in less geothermal activity, less plate movement, and fewer volcanos. The same thing has already happened to Mars and the Moon. It just is so big, and started so hot that this process is not going to be completed by the time the Sun consumes the Earth when it dies. So in practice, it’s just going to stay the same temp.
However, there is extra heat being generated from the decay of radioactive metals in the core, but this also decreases over time, and is one of the slower processes in the solar system. Again, it results in just staying the same.
The core and mantle has radioactive elements which decay, producing heat. Also there is a massive amount of heat there, and it’s taking almost forever to cool off. The Sun will destroy Earth much earlier than it can possibly cool down. Even the Moon, which is much smaller than Earth, hasn’t cooled down completely yet, and it even had active volcanoes relatively recently.
There are 3 main sources of heat inside the planet Earth. First, there’s a bunch that has been there since the Earth was formed a few billion years ago and it hasn’t come out yet. It’s slowly making its way from the inside to the outside. There’s also heat caused by friction as things churn and heavier things make their way closer to the core. Finally, there’s heat from the decay of heavy radioactive elements that we don’t have up here on the surface.
So there’s more heat below waiting to replace anything that’s leaked through the surface. Overall, it’s cooling off, but not so you would notice over a short time frame like a human life time.
There is no magma in the middle of the earth. The inner core is solid metal and the out core is liquid metal. The center is very warm, it is hotter the the surface of the sun, the reason it is solid is because of the high pressure
Around the core, you have the malte that is made of silicate rock. It is predominantly solid, but in geological time it behaves as a viscous fluid. The reason it is solid is the hight pressure.
Magma is molten or semi-molten material. It is material from the crust or the mantle. It is just below or in the crust.
There is two main part of why the center of the earth is warm.
One major part is that all the heat generated when the earth was formed and all materials collided still has not escaped. The crust works as a layer of insulation.
Large objects take a long time to cool because the heat escapes through the surface and the volume-to-surface ratio is smaller the larger the object is. A human has a volume of around 0.1 cubic meters and a surface area of 2 square meters. that is a ratio of 0.1/20= 0.005
The volume of a sphere is 4/3pi r^3 and the surface area is 4pir^2. So the area-to-volume ratio is 4/3pi r^3 /4pir^2 = r/3. Earth’s radius is 6371000m so a ratio of 2,123,666 This meant the volume compare to the surface is around 400 million times larger than a human. The rated heat is lost for the large objects is not comparable to the small object we are used to in everyday life
So cool down time for an earth-sized object just because of this is hundred of million to billion of years. It is not enough to explain what we observe but a major part of it.
The second part is the radioactive decay of material in Earth. The released energy will be converted to heat It is primary Uranium, thorium, and potassium that release energy that way. The amount of energy released today is equal to around 50% of the energy that escapes from earth’s internals to the surface. The half-life of that element is 700 million to 4.5 billion of years, which is why they still exist. Earth is also around 4.5 billion years old so the initial energy they release will be more than double, adding to that shorter-lived element that is gone today.
So there is no magma in the core of earth, it is close to the surface. The inner part of Earth is still hot, it is just not magma.
The reason the inner part is hot is the remaining energy from the formation of Earth that take an enormous time to escape a large object like a planet plus the heat that radioactive decay produced.
The Earth’s crust is losing energy over time however there are some processes which are generating heat, there are atoms of Uranium and other heavy elements which are naturally undergoing decay which releases energy like a nuclear reactor, the core of the Earth is also under pressure and as the Moon orbits the Earth the Earth is slightly squeezed which generates heat.
In addition to the other answers, the amount of heat lost to the surface through the things you describe is microscopic compared to the heat stored. It’s not even a fraction of a percent.
> how is core temperature sustainable?
it’s not, the vast majority is the heat in the core is from radioactive decay, and the rest is a combination of friction and the pressure caused b ythe pull of the sun and vice versa.
its gonna make several million years, but Earth’s core eventually will cooldown(honestly the Sun might die out 1st.)
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